The invention relates to a distribution device as for slurries, especially concrete. The distribution device has a distributing boom supporting a concrete-conveying conduit. The distributing boom consists of several sections, which can be folded towards each other. At least one of the several sections is telescopic, having at least a first telescopic pipe and a second telescopic pipe that can be extended from the first telescopic pipe. The concrete-conveying conduit is designed in the region of the telescopic distributing boom section as a system consisting of several articulated conveying-conduit elements in order to ensure lengthwise adjustment of the concrete-conveying conduit to the telescopic movement. One of said conveying-conduit elements is articulated at one end with the first telescopic pipe. The other conveying-conduit element is articulated at one end with the second telescopic pipe. The articulation points of the two conveying-conduit elements are articulated with the two telescopic pipes. The two telescopic pipes alternately assume essentially transposed positions in the two telescopic end positions, so that the one telescopic pipe is retracted and extended into its telescopic end positions, the two articulation points move past one another. The conveying-conduit elements are extended against the direction of concrete conveyance in one telescopic end position and in the direction of concrete conveyance in the other telescopic end position.
Such distribution devices are used in particular to convey concrete in building construction, for example, to pour concrete ceilings in buildings. Depending on the height and size of the building, the concrete may have to be distributed over a wide area. For this purpose, distribution systems are used, which are mounted on a transport vehicle, a crane or the like and which mostly consist of a distribution boom divided into several boom sections. The prime concern in respect of the distribution booms is to achieve maximum distribution reach for concrete conveyance, a requirement satisfied by skillful division of the boom into individual boom sections that are connected with each other in an articulated or telescopic manner.
This is why highly sensitive, articulated distribution booms are a characteristic of mobile concrete pump systems. The distribution booms are disposed on a pivot mounting and support a concrete-conveying conduit. Such distribution booms can assume the most varied types of work positions that may be required at the job site, e.g. vertical or horizontal extension, angular positions, etc. Regardless of their configuration, the booms thus enable the delivery end of the concrete-conveying conduit to be guided precisely to the place at which the concrete is to be poured. The tip of the distribution boom is guided by turning the latter and/or adjusting the angles between the individual boom sections.
The distribution boom""s high degree of mobility is especially important at its front end, i.e. in the vicinity of concrete delivery. For the section nearer the pivot mounting, by contrast, the telescopic function is more important because of the height and width of reach that it permits. In this context, it has proved expedient to design at least one section of the distribution boom, preferably the basic boom, as a telescopic section. Compared to the alternative of bringing the boom sections into angular positions, this solution has the advantage of requiring less space.
For the telescopic section of the distribution boom, provisions must be made for lengthwise adjustment of the concrete-conveying conduit. Of course, lengthwise adjustment may be achieved by using flexible concrete-conveying-conduit elements in the region of the telescopic boom section. Such a solution, however, is restricted to small extension/retraction lengths, since flexible concrete-conveying conduits can only be bent to a limited extent. In cases involving greater extension/retraction lengths, such a design is out of the question. Here, rigid concrete-conveying-conduit elements must be used instead.
In a known distribution device of the same type, described in U.S. Pat. No. 4,130,134, the distribution device is supported on a pivot mounting of a truck. This distribution device has a telescopic basic boom, and lengthwise adjustment of the concrete-conveying conduit is achieved by means of a scissor-type system consisting of several conveying-conduit elements. The known scissor-type conveying conduit for lengthwise adjustment to the telescopic travel of the basic boom uses at least three conveying-conduit elements which are connected in series. The conveying-conduit elements are arranged in such a manner that they can be folded variably between a fully folded position when the telescopic section is fully retracted and a fully extended position, when the telescopic section is fully extended. During the telescopic process, every conveying-conduit element swings by about 180xc2x0 and, at one stage, assumes a position perpendicular to the telescopic axis. The known scissor-type conveying conduit requires at least three conveying-conduit elements, of which the two outer elements are each articulated at one end with the central conveying-conduit element. With their respective other ends, the outer elements are connected with the respective telescopic section of the distribution boom and there with the concrete-conveying conduit that supplies or carries off the concrete. Basically, however, these two outer of the three conveying-conduit elements are insignificant for lengthwise adjustment to the telescopic travel. Compared to the telescopic pipes which support them, the outer elements only perform an insignificant dodging movement perpendicular to the longitudinal axis of the telescope and only move to the extent to which the articulation points with the central conveying-conduit element move away at right angles from the telescope""s longitudinal axis during the telescopic process. Thus, lengthwise adjustment to the telescopic boom section is effected exclusively by the swiveling of the middle conveying-conduit element. This middle element is supported centrally on a member which is guided on the distribution boom in longitudinal direction, and because of the arrangement surrounding the boom profile, can only swing up to about 120xc2x0. As a result, only about 1.7 times the actual length of the central conduit element can be used for lengthwise adjustment to the telescopic boom section. If the telescopic boom section is extended by approximately 50%, a position at which the central conveying-conduit element forms an angle of approximately 90xc2x0 to the telescopic boom section, this concrete-conveying-conduit element protrudes on both sides of the distribution boom by approximately one-fourth of the telescopic length, so that the entire system size of such a device amounts to approximately half the telescopic length. With telescopic lengths of 4 to 6 m commonly encountered in practice, this is extremely irritating.
The U.S. Pat. No. 4,130,134 does in fact suggest an alternative two-fold scissor-type conveying conduit for systems involving great telescopic lengths or multiple telescopic sections. However, this suggestion has the disadvantage that for each additional scissor-type conveying conduit, additional conveying-conduit elements would have to be used, i.e. one element relevant for lengthwise adjustment to the telescopic boom and one intermediate connecting element which is irrelevant for lengthwise adjustment. This inevitably adds considerably to the cost of the construction and requires a complex arrangement of concrete-conveying-conduit elements.
The known concrete distribution device thus has the disadvantage that widthwise it requires rather a lot of space. This presents a problem in view of the fact that with such distribution devices a large number of folded boom sections together with the multisection concrete-conveying conduit they support and further distribution-device accessories must be accommodated in a very confined space. Accordingly, increased importance is attached to a more compact and simple design of such distribution devices with a telescopic boom section.
It has been suggested that the concrete-conveying conduit itself be designed with a telescopic function (German patent specification 196 41 789). This, however, involves the problem that in the telescopic section, the concrete hardens between the inside and outside concrete-conveying conduits. This seriously interferes with conduit retraction and extension and with cleaning, and may even render these actions impossible. The guidance of the telescopic conduit sections into one another and the problems associated with their roundness have so far prevented such a design from being implemented in practice.
Finally it is known from U.S. Pat. No. 3,942,554 that in the case of a telescopically adjustable crane boom supporting a conveying conduit, the conduit length can be adjusted as the crane boom is extended or retracted by articulating two movable interconnected conduit sections with the front and rear ends of the telescopic boom section in such a way that the conveying conduit folds and unfolds with Z-like movement when the crane boom is retracted/extended (cf. FIG. 1 and FIGS. 6 and 7). When the boom is retracted, the conveying-conduit elements move from their extended positionxe2x80x94which, when the boom is fully extended, is approximately parallel to the telescopic directionxe2x80x94to a position which, when the boom is fully retracted, is approximately perpendicular to the telescopic direction, or vice versa. During this process, the conveying-conduit elements swing by approximately 90xc2x0, which would necessarily result in a system height of approximately half the telescopic length. For telescopic lengths of 4 to 6 m, which are commonly encountered in practice, such a design would be exceptionally irritating, since it requires a lot of space during unfolding of the system and, besides, involves increased constructional costs.
EP-A 432 854 describes a distribution device of the same type, in which two conveying-conduit elements are in a transposed position relative to each other in one telescopic end position and are on a sloping plane relative to each other in the other telescopic end position. The two conveying-conduit elements move past each other during the extension of the one telescopic element. However, the assembly consisting of the two interconnected conveying-conduit elements is relatively awkward in shape, which in view of the many moving parts combined in the distribution device is disadvantageous and irritating during unfolding or extension of the boom.
The object of this invention is to provide a distribution device, especially suitable for concrete conveyance, which is of relatively simple and structurally compact design and allows lengthwise adjustment of a concrete conveying conduit to a telescopic supporting boom.
This object is established according to the invention by means of the features contained in the characterizing part of claim 1 with useful embodiments being characterized by the features contained in the subclaims.
As provided for by the invention, each conveying-conduit element is designed such that its end portions curve in the same direction and point towards the end portions of the other conveying-conduit element. This results in an essentially xe2x80x9cS-shapedxe2x80x9d design when the conveying-conduit elements are in extended position. This leads to a highly compact design, which is very advantageous for the distribution device because the latter has many moving parts which must not impede each other when the boom sections are extended or unfolded. The articulation points of the two conveying-conduit elements articulated with the telescopic pipe alternately assume essentially transposed positions when the telescopic pipe is either fully retracted or fully extended. During extension or retraction of the extensible telescopic pipe into its end positions, the two articulation points of the conveying-conduit elements move past each other with the conveying-conduit elements assuming an extended position in both telescopic end positions, in one end position against the direction of concrete conveyance and in the other end position in the direction of concrete conveyance.
The two conveying-conduit elements, which are relevant for lengthwise adjustment, have a length equal to about one-fourth of the travel of the telescopic boom section. During the entire telescopic process, each of the conveying-conduit elements moves by approximately 180xc2x0, thus assuming at one stage a position perpendicular to the telescopic direction. Application of the roll-folding principle provided for by the invention ensures that the two conveying-conduit elements never assume this vertical position simultaneously but always one after the other. This means that the height of the system, i.e. the space required, amounts to approximately one-fourth of the telescopic travel or roughly the length of one conveying-conduit element. This is advantageous for compact scissor-type conveying-conduit design. Not only can the entire system height depending on the number of conveying-conduit elements, amount to only approximately one-fourth or less of the telescopic travel, but, what is more, the system does not require any intermediate pieces, so that additional constructional costs associated therewith are avoided. Overall, this also reduces the number of moving parts and the necessary joints, as well as means to support them.
An additional advantage is that by freely determining the lengths of the conveying-conduit elements and their articulation with the two telescopic pipes which perform a sliding movement relative to each other, the scissor-type conveying conduit can be tailored to the situation predefined by the transport vehicle and the distribution boom to be used.
It has proved expedient if the points at which the conveying-conduit elements are articulated with the telescopic pipes that can be moved relative to each other are positioned at different heights (from each other), so that the articulation points of the conveying-conduit scissor form a statically defined triangle at each stage of telescopic movement. As a result, the forces acting upon the conveying-conduit elements are also statically defined at each stage. This is important for the design, stability and service-life of the structure. In this case, the articulation points move on exactly defined paths, with the fixed articulation points moving relative to each other on paths parallel to the telescopic direction.
Thus, the invention not only realizes the low system height which is crucial for complicated distribution booms and their motions but also makes it possible to tailor the design and arrangement of conveying-conduit elements relevant for lengthwise adjustment, and their articulations, to the constructional environmentxe2x80x94a factor that is crucial in view of the complexity of today""s concrete distribution booms. In this context, it must be borne in mind that there is relatively little room available for the installation and movement of concrete distribution devices consisting of various boom segments because parts of the drive system, such as cylinders, levers etc., which are required for swiveling the distribution boom, also have to be accommodated in this extremely confined area.
It has also proved expedient to design each conveying-conduit element roughly in the shape of a xe2x80x9cCxe2x80x9d, so that two adjoining conveying-conduit elements that are directly connected with each other by means of an articulated joint, result essentially in an xe2x80x9cSxe2x80x9d or xe2x80x9cwave shapexe2x80x9d with two opposing amplitudes. This design allows the two elements to move past each other while requiring only little space.